I am not a "show people" as I've never been in the ring, and only have the one dog that actually finished her championship, but I keep collars on my dogs 24/7.
I used the rolled leather collars, and they don't leave any marks on the neck at all – necks are nice and smooth.
Well, really they do leave marks… but they are pretty little.... I always don't leave collars on in the house for a number of reasons... (this is after they get used to them of course)... 1. I am always afraid that they will get a mouth caught in them when playing... and 2. they will/could get hung up on something... however that said, mine are not crated, as we have a doggy room for them.. and they have a doggy door to a secure fenced yard.